Could a seemingly harmless virus you had as a baby be behind coeliac disease?
New research suggests an infection with a common strain of reovirus, which is often symptomless, could be behind why some people’s immune systems react to gluten as if it were a dangerous pathogen instead of a harmless food protein.
The research, published today in Science, found mice engineered to be genetically susceptible to gluten intolerance who were infected with the reovirus strain T1L went on to have an immune response against gluten.
The virus in question is so harmless that people often don’t even realise they have been infected, according to University of Pittsburg virologist Terence Dermody, who worked on the study.
But if the first exposure to a food with gluten occurs during a reovirus infection, the virus may turn the immune system against the food protein, Professor Dermody and his colleagues found.
What is coeliac disease?
- It’s an immune response to gluten, a protein found in wheat, rye, barley and oats
- It causes damage to the small bowel, leading to a reduced surface area for nutrient absorption
- Only 1 in 30 people with a genetic susceptibility to coeliac will actually develop the disease
- 80 per cent of Australians with coeliac disease remain undiagnosed
- Coeliac disease cannot be cured, but people can manage the condition through a gluten-free diet
The immune system can either allow foreign substances, such as food proteins, to pass through the body peacefully, or it can go on the attack.
In people with coeliac disease, the protein gluten is treated like a harmful pathogen. The immune system response damages the lining of the small intestine, causing symptoms like bloody diarrhoea.
Dr Jason Tye-Din, head of coeliac research at the Walter and Eliza Hall Institute of Medical Research in Melbourne, did not work on the study but said the research was a “big leap” in understanding how coeliac disease can develop.
“The significance of this work is that it provides a mechanism for how virus infection might actually trigger the disease,” Dr Tye-Din said.
“Epidemiologic studies show infection could be a trigger but no-one’s ever really shown how that would happen.”
Dr Tye-Din said about half the Australian population were genetically susceptible to coeliac disease, but that environmental factors — which are still not understood in detail — were involved in activating the disease.
This research was a step in the direction of understanding how these environmental triggers worked, he said.
Could we one day see an anti-coeliac vaccine?
Professor Dermody said he does not think that the T1L reovirus, which was used in the study, is the only virus that can stimulate coeliac disease.
Future research will analyse the potential of other viruses and also determine whether T1L was a true trigger of the disease in humans.
If it is, then a reovirus vaccine could be developed for at-risk children, which could potentially block the development of the disease, “and that would be pretty amazing”, Professor Dermody said.
Dr Tye-Din was cautious about the logistics of vaccinating babies against an often symptomless virus based on genetic predisposition — but said the implications of the research could be even broader than just for coeliac disease.
It could help unlock the triggers for other food allergies and autoimmune diseases.
“[The research] raises a possibility that infections such as this might be underlying a range of abnormal immune responses to other food proteins or even triggering other autoimmune diseases,” he said.
“What its saying is, here’s a mechanism for how what otherwise might seem to be harmless virus might confuse the immune system into thinking something’s a harmful protein.”